Hey!
Hope this helps...
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Car #1: 300/43.2 = 6.9444 gallons
(Rounded) Car #2: 300/35.9 = 8.3565 gallons
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(Rounded) Car #1: 6.9444*3.19 = $22.16 to re-fill their tank
(Rounded) Car #2: 8.3565*3.19 = $26.66 to re-fill their tank
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(Rounded) Difference: $26.66 - 22.15 = $4.50
To re-fill Car 2's tank is approximately $4.50 more to re-fill Car 1's tank...
It would be B. -6.
f(x) = 3x-12
f(2) = 3(2)-12
f(2) = 6-12
f(2) = -6
I'm not very good with word problems but if I am correct it is 660 minutes so about 11 hours?